Leon Kossoff’s paintings at Mitchell-Innes & Nash show the octogenarian British painter continuing to work in portraiture and landscape, with a brush loaded with oils as if they were tar, favoring a palette based on a sooty, British gray. In that, there has hardly been any change in his work for decades. But comparing these works to those in the gallery in 2009, which were from the period 1957 to 1967, one can see a brightening. He has admitted green into the paintings, a verdancy unmixed with ashes as would have been his wont fifty years ago.

It was perhaps necessary to offset the unavoidable symbolism in the recurring subject of his work over the last decade, a tree propped up on two stakes as if upon primitive crutches. A note from Kossoff dated July 2010 explains, “These paintings are about one tree. A cherry tree in a garden that may have been part of an orchard before the nearby house was built. One large bough was deteriorating and should have been removed. Instead, we decided to support it with stakes. As time passed it seemed as if the stakes had always been there. This subject, so different from other subjects that I had been involved with through the years, became my working life. Time passed, and paintings of the tree emerged together with the [models’] heads…”

The artist gives us no reason to interpret the tree as anything but itself. But there it is, ancient, half-toppled, held up by human interventions, and yet growing upwards and outwards in fine weather hardly ever seen before in Kossoff’s oeuvre. Cherry Tree, Early January (2004), though its surface is no less clotted than is typical of him, is suffused with yellow warmth. In Cherry Tree, with Diesel (2004-5), a train speeds by in the background, brushed out in smears of paint that lend it a Futurist velocity. Life goes by; the tree persists, reclining in the sun, if not leisurely or wholly by choice. It’s as fine a metaphor for a good old age as anything ever painted. When other paintings of the same subject return to the overcast norm, they get a boost of vitality for the artist having proven that they appear as such due to his command, not out of habit.

Christchurch Spitalfields, the Hawksmoor church that Kossof has studied with a sustained intensity that recalls Monet’s serial meditations on the facade of Rouen Cathedral, gets similarly refreshed treatments. The gray outlines and pitched perspective of the architecture is there as before in his work, but in a five-foot panel from 2000 it appears sandwiched between a hesitantly blue sky (cheerful by Kossoff’s standards) and a mighty green canopy, presumably a line of trees of which we see the trunk of the first.

Longtime sitters John and Peggy reappear as well. The artist’s portraits can come off as vicious. This is especially true of the early works – with all the slathering of gray oils, people in Kossoffs sometimes look as though they’ve been portrayed as a pile of octopuses. But even here the colors have sweetened into pinks and greens, and the Venetian red line that holds them together verges on the calligraphic. A tenderness and humanity has entered into them where there was once a predominance of bombastic, albeit gifted, brushwork. After a series of head-and-shoulder portraits of John, the full-length one from 2006 depicting him in a wheelchair, alongside a dozing Peggy, comes as a shock. But the greenery beyond the window and the glad blue of the floor set him up for consideration akin to the cherry tree, assisted, but still participating in life.

“Everyone has talent at twenty-five,” said Degas. “The trick is to have it at fifty.” So what’s the trick? No one ever willed talent into being. (Skill, yes; talent, no.) One can only sow effort year after year and hope that one’s creative soil is rich enough to produce. Kossoff, who would be in a position to note that the real trick is to have talent at 85, shows the way. The persistent, vigorous exercise of his gifts has resulted in a visual spring at a time when one might expect an artist’s winter.